Method and  device for producing a fiber-reinforced thermoplastic composite component

ABSTRACT

Disclosed is a method for the manufacture of a fibre-reinforced thermoplastic composite module from a multiplicity of module components, which are continuously moved in the feed direction and are connected together section-by-section by means of a pressure application head that can be traversed in the feed direction and in the counter-direction; also disclosed is a device for the execution of the method.

The invention concerns a method for the manufacture of afibre-reinforced thermoplastic composite module in accordance with thepreamble of claim 1, for example, a shell element of an aircraftfuselage, and a device for the execution of the method in accordancewith the preamble of claim 9.

Fibre-reinforced composite modules, such as shell elements of anaircraft fuselage, have in a manner of known art a backing structureformed from a multiplicity of longitudinal stiffeners, which aredirectly connected to a skin field, and a multiplicity ofcircumferential stiffeners, which are connected to the skin field viafittings, e.g. clips, and in addition are supported on the longitudinalstiffeners via supporting elements, e.g. cleats.

The manufacture of such fuselage segments is undertaken using either adifferential form of construction or an integral form of construction.In the differential form of construction the individual components areproduced separately from one another and are then assembled to form thecomplete module. What is particularly disadvantageous in this form ofconstruction is the time- and cost-intensive assembly of the completemodule. In addition the differential form of construction requires amultiplicity of connecting elements for purposes of connecting themodule components together. The integral form of construction, in whichthe individual components are produced in an integral manner as acomplete module, features a reduced assembly effort and, by virtue ofthe increase in the level of integration, a greater production effort.For purposes of reducing the production effort the patent U.S. Pat. No.6,613,258 B1 proposes, for example, the manufacture of a fuselage barrelfrom fibre-reinforced thermoplastic composite materials. Here curedlongitudinal stiffeners are laid in depressions of a cylindrical core.The core is then set in rotation about its longitudinal axis and aweb-type laminate is wound onto the core. The laying down of thelaminate is undertaken via a laying down head with the application oftemperature and pressure, as a result of which the thermoplastic matrixis in a molten state and the laminate is welded securely to thelongitudinal stiffeners. Disadvantageous in this solution, however, arethe very tight production tolerances on the fuselage barrels.

The object of the present invention is to create a method for themanufacture of a fibre-reinforced thermoplastic composite module, whichremoves the above-cited disadvantages and forms an optimal compromisebetween the production effort, the assembly effort and the productiontolerances, and also a device for the execution of this method.

This object is achieved by means of a method with the features of claim1, and by means of a device with the features of claim 9.

In an inventive method for the manufacture of a fibre-reinforcedthermoplastic composite module, which consists of a multiplicity ofmodule components and is, for example, a shell element of an aircraftreinforced with stiffening elements, the module components arepositioned relative to one another by means of a jig reproducing thegeometry of the composite module. In accordance with the invention themodule components are continuously moved in the feed direction and areconnected to one another section-by-section by means of a pressureapplication head that can be traversed in the feed direction and in thecounter-direction. The inventive method generates an optimal compromisebetween the assembly effort, the production effort and the productiontolerances. While it is true that the shell mode of constructionincreases the production effort compared with the wound barrel mode ofconstruction, the shell mode of construction allows for an improvedtolerance compensation. The inventive solution brings together varioustechnologies, such as the pressing and welding of thermoplastic modules,in a continuous production process for the manufacture of large modules.As a result of the continuous movement of the module components in thefeed direction, and as a result of the ability of the pressureapplication head to traverse in the feed direction and in thecounter-direction, the pressure application head can be embodied in acorrespondingly compact manner. The size of the module isquasi-decoupled from the size of the pressure application head, so thatany, or almost any, size of thermoplastic composite module can bemanufactured using the inventive method.

In a preferred example of embodiment the pressure application head, forpurposes of connecting the module components, is traversed out of astarting position in the feed direction of the module components, andafter the connection of the module components, is then moved in thecounter-direction. By this means the pressure application head is guidedin a quasi-circle, which makes possible a relatively simple controlsystem. The movement of the pressure application head in the feeddirection and the counter-direction can be embodied in a particularlysimple manner, if, after the pressure application head has been raised,it is moved back to the starting position.

In particular, the movement of the pressure application head in the feeddirection is determined in accordance with its length in the feeddirection. The pressure application head preferably has a length in thefeed direction that is larger than a feed increment. This guaranteesthat during the pressure application process the pressed regionsoverlap, thus ensuring that the module components are welded oradhesively bonded to one another over the whole composite module.

In one example of embodiment at least one of the module components, forexample a laminate for the manufacture of the skin field, iscontinuously laid down ahead of the pressure application process. Bythis means the storage of the respective module components iseliminated, so that long transit times as a result of transfer betweenvarious means of production are not necessary. Here it is advantageousif at least one module component is heated before the laying downprocess such that its thermoplastic matrix is in a molten state.

At least some of the module components are preferably laid down on thetool mould in the solidified state (thermoplastics do not “cure” in thesame way as thermosetting plastics). In particular this eases thehandling of the module components and their positioning on the toolmould.

To achieve a defined polymer structure it is advantageous if the modulecomponents are cooled in a controlled manner while they are beingconnected by the pressure application head.

An inventive device for the manufacture of a fibre-reinforcedthermoplastic composite module has a tool mould for purposes ofpositioning individual module components relative to one another; thiscan be moved in a feed direction; the device also has a pressureapplication head that can be traversed in the feed direction and in thecounter-direction for purposes of welding the module components. Theinventive device enables the continuous production of large modules,such as shell elements for an aircraft fuselage, for example, which arereinforced by means of a backing structure. At the same time the devicecan be embodied in a very compact manner, since the pressure applicationhead, by virtue of its ability to traverse in the feed direction and inthe counter-direction, need not extend over the total length of the toolmould in the feed direction. The inventive device enables the movementof the pressure application head in a quasi-circular path, so that thepressure application head itself only has to be a fraction of the lengthof the tool mould in the longitudinal direction. At the same time thecompactness of the pressure application head can be increased further ifthis can also be moved in the transverse direction.

For purposes of achieving a high level of consolidation it isadvantageous if at least one heating device, or example an inductionwelding device, is arranged in each case in the tool mould region inwhich the module components are to be accommodated.

Other advantageous examples of embodiment of the present invention arethe subject of further subsidiary claims.

In what follows preferred examples of embodiment of the presentinvention are elucidated in more detail with the aid of schematicrepresentations. Here:

FIG. 1 shows a cross-section through an inventive device, and

FIG. 2 shows an inventive method.

In the figures the same constructive elements bear the same referencenumbers, wherein in the interests of clarity in the case of a pluralityof the same constructive elements in one figure only one element isprovided with a reference number.

FIG. 1 shows an inventive device for the manufacture of afibre-reinforced shell element 2, reinforced, for example with carbonfibres, on a thermoplastic base for the manufacture of an aircraftfuselage. The shell element 2 consists of a fibre-reinforcedthermoplastic skin field 4 and a multiplicity of integralfibre-reinforced thermoplastic longitudinal stiffeners 6 for purposes ofreinforcing the skin field 4. Further stiffeners, such ascircumferential stiffeners, are not represented in the interests ofclarity. These can similarly be designed integrally with the skin field4, or can be connected subsequently.

The device 1 has a lower tool mould 8 and an upper pressure applicationhead 10. The tool mould 8 can be traversed in the longitudinal directionand has a concave surface 12 corresponding to the geometry of theaircraft fuselage for purposes of laying down laminate layers to formthe skin field 4, in which a multiplicity of depressions 14 extending inthe longitudinal direction of the tool mould 8 are designed for purposesof accommodating the longitudinal stiffeners 6. In the example ofembodiment shown the longitudinal stiffeners 6 are designed as omegaprofiles; these are welded or adhesively bonded to the skin field 4 inthe region of their foot sections 16. For purposes of achieving a highlevel of consolidation the foot sections 16 are supported in each caseon a heating device 18, or example an induction welding device, arrangedin the region of the depressions 14.

The pressure application head 10 has a convex counter-surface 20 shapedin a complementary manner to the tool mould 8; this extends essentiallyover the whole width of the surface 12, so that the skin field 4 in onepressure application can be fully clamped in the transverse directionbetween the pressure application head 10 and the tool mould 8. It can betraversed via at least one cylindrical ram arrangement 22 orthogonallyto the tool mould 8. In addition the pressure application head 10 can betraversed in the feed direction and in the counter-direction of the toolmould 8. For purposes of achieving controlled cooling the pressureapplication head 10 has a heating device, not shown, for example aninduction heating device.

In what follows an inventive method for the manufacture of a shellelement 2 for an aircraft fuselage, i.e. for the activation of thedevice 1, is described with the aid of FIG. 2. Firstly the fully orpartly consolidated fibre-reinforced thermoplastic longitudinalstiffeners 6 are positioned in the depressions 14 of the tool mould 8.The fibre-reinforced thermoplastic laminate is then continuouslysupplied onto the surface 12 to form the skin field 4, and thus over thefoot sections 16 of the longitudinal stiffeners 6. The laminate layershave previously been heated in a furnace, not represented, such thattheir thermoplastic matrix possesses a viscosity that is suitable forthe pressure moulding process during the laying down process on the toolmould 8. The pressure application head is heated to a temperaturematched to the desired material properties of the thermoplastics, andfrom its starting position executes a lowering movement 24 in thedirection of the laid down molten laminate layers, so that the latter,by means of the application of pressure and temperature, are welded tothe foot sections 16 of the longitudinal stiffeners 6 and moreover arelaid down on the surface 12 such that they conform to its contour andthere solidify. At the same time at least the contact points of the skinfield 4 and the longitudinal stiffeners 6 that are to be welded areheated in a controlled manner via the induction welding devices 18 inorder to promote the welding process. The tool mould 8 and the pressureapplication head 10 are then moved in the longitudinal direction L, i.e.the feed direction 26, with the same velocity, so that the relativevelocity between the tool mould 8 and the pressure application head 10moving in the same direction is equal to zero. After a defined pressureapplication time the pressure application head 10 is activated such thatit executes a raising movement 28 in the direction away from the toolmould 8. The tool mould 8 continues to execute a continuous feedmovement in the longitudinal direction L. After the raising of thepressure application head 10 this is guided back to its startingposition via a movement 30 in the counter-direction. After it hasarrived at its starting position the pressure application head hasdescribed a quasi-circular movement, which is repeated until the skinfield 4 is welded to the longitudinal stiffeners 6 over its wholelength. At the same time the pressure application head 10 during thecounter-movement 30 is advanced by the same amount as during the feedmovement 26. However, the movement of the pressure application head 10in the feed direction 26 corresponds to a fraction of the length of itsbody in the feed direction 26, so that with each circular movementregions of overlap are formed between the pressure application head 10and the skin field 4, and at least small regions, if not each skin fieldsection, are twice subjected to temperature and pressure. After thewelding of the skin field 4 to the longitudinal stiffeners 6 the shellelement 2 is extracted from the tool mould 8, i.e. the required skinfield length is detached from the skin field section that iscontinuously exiting the press, and is fed through to any furthermechanical processes for the smoothing of module edges, the introductionof window apertures, door apertures, and similar.

Disclosed is a method for the manufacture of a fibre-reinforcedthermoplastic composite module from a multiplicity of module components,which are continuously moved in the feed direction and are connectedtogether by sections by means of a pressure application head that can betraversed in the feed direction and in the counter-direction; alsodisclosed is a device for the execution of the method.

REFERENCE SYMBOL LIST

-   1 Device-   2 Shell element-   4 Skin field-   6 Longitudinal stiffener-   8 Tool mould-   10 Pressure application head-   12 Concave surface-   14 Depression-   16 Foot section-   18 Heating device-   20 Convex counter-surface-   22 Cylindrical ram arrangement-   24 Lowering movement-   26 Movement in the feed direction-   28 Raising movement-   30 Counter-movement in the counter-direction-   L Longitudinal direction/feed direction

1. A method for the manufacture of a fibre-reinforced thermoplasticcomposite module (2), from a multiplicity of module components (4, 6),for example a shell element for an aircraft that is reinforced withstiffening elements; the module components being positioned relative toone another by means of a jig (8) reproducing the geometry of thecomposite module (2), characterised in that, the module components (4,6) are continuously moved in the feed direction (26) and are connectedto one another section-by-section via a pressure application head (10)that can be traversed in the feed direction (26) and in thecounter-direction (30).
 2. The method in accordance with claim 1,wherein during the connection of the module components (4, 6) thepressure application head (10) is traversed out of a starting positionin the feed direction (26) of the module components (4, 6) and thenexecutes a movement in the counter-direction (30).
 3. The method inaccordance with claim 2, wherein the pressure application head (10) ismoved back to the starting position.
 4. The method in accordance withclaim 1, wherein the pressure application head (10) has a length in thefeed direction (26) that is greater than its feed increment.
 5. Themethod in accordance with claim 1, wherein at least one of the modulecomponents (4) is continuously laid down on the tool mould (8).
 6. Themethod in accordance with claim 5, wherein the at least one modulecomponent (4) is heated before it is laid down on the tool mould (8). 7.The method in accordance with claim 1, wherein at least one of themodule components (6) is supplied to the tool mould (8) in thesolidified state.
 8. The method in accordance with claim 1, whereinduring the connection of the module components (4, 6) by means of thepressure application head (10) they are cooled in a controlled manner.9. A device (1) for the manufacture of a fibre-reinforced thermoplasticcomposite module (2) in accordance with the method in accordance withclaim 1, with a tool mould (8) that can be traversed in the feeddirection for purposes of positioning the module components (4, 6)relative to one another, and with a pressure application head (10) thatcan be traversed in the feed direction (26) and in the counter-direction(30) for purposes of connecting the module components (4, 6).
 10. Thedevice in accordance with claim 9, wherein at least one heating device(18) is arranged in each case in the tool mould (8) in the region of themodule components (4, 6) to be accommodated.